Electron discharge device



R. H. WILSON.

ELECTRON DISCHARGE DEVICE.

APPLICATION FILED IULYIG, 1919.

1,403,932, Patented Jan. 17, 1922,

PNITED sTArss BAT OFFICE.

RICHARD H. WILSON, OF NEWARK, NEW JERSEY, ASSIGNOR T0 WESTERN ELIXITRICCOMPANY, INCORPORATED, OF NEW YORK, N. Y A CORPORATION 01 NEW YORK.

ELECTRON DISCHARGE DEVICE.

Application filed July 16,

To ail whom it may concern Be it known that I, RICHARD H. WILSON, asubject of the King of Great Britain, residing at Newark, in the countyof Essex, State of New Jersey, have invented certain new and usefulImprovements in Electron Dischar e Devices, of which the following is aful clear, concise, and exact description.

This invention relates to electron discharge devices in which theimpulses to be amplified, repeated or rectified are applied to a controlelectrode such as a grid. It has been found that in devices of thistype, a coated filament having been employed, a potential differencewhich may be called a contact difference in potential actually existsbetween the grid and the filament when a current is flowing from thefilament to the plate. This potential difference assumes differentvalues for different tubes even in the case where precautions are takento employ as near as possible the same material for the grid and thesame sort of alkaline earth oxide coating for the filament. Thisdifference in potential makes it impossible to always use precisely thesame circuit arrangement for the vacuum tube if identical results are tobe obtained.

In any case, however, this difference in.

potentlal is such as'to cause no serious difference in the operation ofthe tube, especiallyfif it is to be employed for amplifying largeimpulses, but in case the tube is to be employed as a detector oramplifier of weak impulses, it is desirable from a manufacturingstandpoint that identical circuit arrangements should give identicalresults.

If the contact difference in potential has a tendency to a positivevalue, it is found necessary in certain circuits, such as amplifiercircuits, to apply a negative potential to the grid in order to make itnegative with respect to the filament. This negative value is desirablein order that no current can flow in the grid-filament circuit of avacuum tube.

The usual method of applying the negative grid potential is to employeither a separate source, such' as a dry cell, or to employ a resistancein the filament circuit, the drop in potential across this resistancebeing supplied to the grid. In both cases the negative potential isapplied to the grid irrespective of the value of the contact differencein Specification of Letters Patent. Patented J an. 17, 1922.

1919. Serial No. 311,211.

This is accomplished by supplying to the grid or control electrode apotential derived from the drop across a resistance which is in circuitwith the source supplying the space current between the cathode andanode.

This resistance is so connected that the grid 7 acquires a negativepotential equal to the drop across it. The drop across this resistanceis proportional to the space current and consequently is dependent tosome extent on the value of the contact difference in potential, since apositive value thereof will increase the space current, which wouldincrease the negative potential of the grid, thereby cutting down thespace current; on

the other hand, a negative value of the contact difference in potentialwill decrease the space current which results in a grid potentialtending to increase the space current. Hence the arrangementcompensates'for variations in this contact difference in potential.

For further details of the invention reference may be made to thedrawing in which the figure represents diagrammatically a circuitembodying the invention.

Referring to the figure in detail, the incoming line 1 is adapted to betraversed by impulses to be repeated substantially without distortion,that is without rectification or modulation and after amplification bythe electron discharge device 2 to be received by the receiver 9 orother translating device. 01' the line 1 may be supplied with modulatedcarrier waves, in which case the vacuum tube 2 may function asa detectorto render the signals audible in the receiver or other device 9.

The tube 2 contains the usual grid 3, cathode 4 and anode 5.

' The grid circuit,

however, in this case includes the resistance 6 which as above describedserves to supply a negative potential to the grid. The drop in potentialacross the resistance 6 is produced by the current flowing from thebattery 7 which supplies the space current between cathode 4 andanodeThe current from battery 7 through resistance Gris main'-. tainedsubstantially constant by the choke coil 8 and the outgoing impulses areled oil of vacuum tube used, that is, with the 7 amount of negative gridpotential desired and the normal plate current. Preferably the value ofthe resistance 6 should be small as compared with the value of thereceiver '9. For instance the resistance 6 may be 1,000 ohmsthe receiver9 about 20,000

What-is claimed is:

1.'An electron discharge device having grid and anode current, animpedance common to said grid and anode circuits, and means formaintaining substantially constant the current 'throu h said impedance.

2. n electron discharge device comprising an anode, a cathode and agrid, a source of space current, a resistance, and a pluralcircuits inshunt to said cathode and y of one of said clrcults comprlsmg saldanode,

circuits, a source of space L source, said resistance and a choke 0011connect d in series, and another of said circuits being the outgoing:circuit.

3. An electron discharge device having grid and-anode circuits, a sourceof space current, an impedance common to said grid and anode circuits,and a choke coil in series with said source and said impedance.

4. An electron discharge device comprising an anode, a cathode, and agrid, a source of space current, an impedance in circuit with saidsource, a choke coil in circuit with said source, means fortransferringthe potential dropacross said impedance to said grid, and a circuit forsupplying to said grid the impulse to be repeated, the sources ofpotential above enumerated being the only sources for assigning to thegrid a potential different from that of said cathode.

5. An electron discharge device comprising an anode, a cathode, a grid,a source of space current, and means for supplying between said cathodeand grid a potential dependent in value upon the current supplied bysaid source and substantially independent of the value of the outgoingimpulse.

In witness whereof, I hereunto subscribe my name this 11th da of July A.D. 1919. RICHA D H. WILSON.

